Press and method of pressing



Sept- 15", 1939- G. FoRlcHoN 2,173,583'- PRESS AND 'METHOD or' PnnSsING Filed lay 22, 1936 6 Sheets-Sheet 1 s? I 9- i g ld I k l /I 'n k N n n N w -1- f 4 n i 1' o Y :o lg

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Q v" El, 28 si -1- Sept. 19, 1939. G. s. FomcHoN 2,173,533

PRESS .AND METHOD-6F PRESSING Filed lay 22, 1936 6`Shets-Sheet 2 6 Sheets-Sheet 3 Spt- 19, 1939- G. s. FoRlcHoN PREss AND METHOD 0E PnEssING Fired nay 22, i936 Sept. 19, 1939. G. s. FoRlcHQN 2,173,533

PRESS AND`METHOD OF PRESSING V I Filed Ilay 22, 1956 6 Sheets-Sheet 4 (il ATT'Y..

Patented Sept. 19, 1939 UNITED STATES PATENT oFr-flcE Application May 22, 1936, Serial No. 81,164 In France April 21, 1936 6 Claims.

Presses are already known, in particular riveting presses, in which a movable head carrying the riveting tool, is .actuated by means of a uid on which two pistons are successively operated; an approach piston of low power and a working piston of high power.

One objectof the present invention is to reduce to a minimum the losses of energy of the driving medium used in carrying outthe work.

A further object is the production of a press which takes care automatically and without control, that the work is executed with pressures of increasing values regardless whether the driving force is increased or not. Still a further object is to produce a portable press of light weight and reduced size.

Riveting presses according to the present invention are illustrated by way of example in the accompanying drawings, in which:

Fig. 1 is a diagram showing the development of the different forces in a riveting press.

Figure 2 is an axial section of the assembly of a press according to the invention.

Figure 3 is a section along the line 3-3 of Figure 2.

Figure 4 is a transverse section along the line 4 4 of Figure 3.

Figures 5 to 7 are axial sections showing the successive positions of themembers of the saidv press during a riveting operation.

Figure 8 is a diagram representing the work done by the press above mentioned.

Figure 9 is a partial axial section of a press according to a modification of Figure 2.

Figures 10 and l1 are two partial axial s'ections showing successive positions of members of the said press.

Figure l2 is a partial axial section of another press according to the invention.

Figures 13 and 14 are two partial axial sections showing successive positions of 'members of the same press.

In a riveting press the riveting operation is carried outin two phases (Fig. 1): an approach y force P which grows in proportion to`the advancement of the working stroke t.

However, in 'the actually known riveting presses, the pressure per square inch applied to the spare head remains' substantially constant 6 during the entire working stroke, whereby it becomes necessary to develop a driving force which in the beginning of the working stroke considerably exceeds the necessary force. The result is a Vconsiderable loss of energy. The driving force l0 spent in the working stroke of the known devices is represented by the area CDEF, whereas the useful working stroke only requires the development of a force corresponding substantially to the force of resistance represented by the area IBI-IEE.

The processesv according to the present invention renders it possible to develop pressure forces which grow progressively and relative to the advancement of the work, so that the diagram 20 of the pressure forces is assimilated to that of the useful work and the loss of energy in the execution of the work is considerably reduced.

'I'he riveting press shown in Figures 2-7 comprises the following principal members: a 25 riveting tool I integral with a moveable working head 3, a transmission cylinder 4, an approach piston 5, a. working piston G, a control member such as a distributor 'I for theoperating iluid.

The movable head 3 is slidably mounted in a 30 cylinder receiver 8, which isscrewed on an extension 91 of the bottom 9 of the transmission cylinder 4.

The said movable head 3 is provided with a shoulder l0 which forms a piston and one of the 35 faces 31 of which receives a packed joint II en suringa fluid-tight seal in one direction between said movable head and its cylinder 8. The other face 3z of the said piston serves as an abutment for a spring I2 which, bearing on a shoulder I3 40 of the cylinder 8, constantly urges the movable head 3 in the direction of its return stroke f1.'

Finally the movable head 3 presents an axial cavity I4 of diameter D3.

The transmission cylinder 4 receives the ap- 45 proach piston 5 which is constituted by a cylindrical body with sliding surfaces 51 52 and a uid tight joint |51 |52.

'I denotes a distribution valve for a pressure fluid, such as compressed air. The valve 1 per- 50 mits the compressed air, which may be delivered by a reservoir of any known type (not shown) to enter through an inlet duct 40, one end of a duct 4I. The other end of the duct 4I terminates at a point close to the face |61 of the approach 55 piston, which face thus receives the pressure of the compressed air, while the other face |62 of the said approach piston 5 is in contact with the transmission liquid; the said liquid is contained in a chamber I1 formed by an extension 11 of the principal cylinder 4 and by the axial space |12 provided in the extension 91 of the bottom of the cylinder 9. The extension |11 thus acts to-supply the feed.

The working piston 6 comprises a plurality of elements each onel of which plays a predetermined part in the operation: a driving piston 61 with a `iluid tight joint I8 is slidably mounted in the approach piston 5 which forms a cylinder for this purpose; the said piston 61 directly receives the pressure of the operating fluid through the duct I9; the working piston proper 62 ofdiameter D6 which is less than D2, slides in a cylinder 20 centeredl in the chamber I1 containing the transmission liquid; a rod 63 forming aplunger piston of diameter d5 less than D connects the piston 61'to the working piston proper 62. The said rod 62 passes through two joints 2|, 22 one of the joints 2| being provided in the bottom 9 of the principal cylinder 4 and the other joint 22 being provided in the face -I 62 of the approach piston 5.

A spiral spring 23 bearing on the inside part of the face |62 oi' the approach piston 5 constantly urges the working piston 6 in the direction f1 of its return stroke.

The chamber I1 containing the transmission liquid comprises a partition 24 which divides the said chamber I1 into two parts |11 |12, an upstream part |11 constituting the transmission chamber proper and a. downstream part |12 relative.to the flow of the liquid during the working stroke of the members of the press. 'I'he down-v stream part |12 forms a single working chamber of uniform cross-section interposed between the transmission chamber |11 and the cylinder receiver 8. l

'I'he partition 24 comprises an oriilce 25 con' ..26 which then puts the two parts |11 |12 of the chamber I1 in communication with each other.

An annular space 32 is provided between the inside wall of the chamberc|1 and the cylinder of the working piston proper 62. 'I'his annular space 32 which also surrounds the spindle 63 at its exit from the joint 2| communicates with the front feed chamber |11 through the orice provided with valves 26.

Ports 33, 34 put the annular space 32 in communication with the inside of the cylinder 20 of the working piston 62.

The distributor 1 is essentially characterized by a'balanced slide valve 11 which slides in a casing 35 and which is actuated externally bymeans of a lever 36. 'Ihe said slide valve 11' controls the ports 31, 38, 39, 391. The ports 39 and 391 are put into communication successively with' When the lever.` 36 is depressed the valve 11 slidesin the direction of the arrow f4. In this Way the valve 11 opens the orifices 39 so that the compressed air can pass from the inlet duct 40 through the port 31 to the channel 4|, which terminates in the bottom of cylinder 4 (Fig. 4). The compressed air conducted into this cylinder acts upon the face |61 of the approach piston 5 to move it in the direction f6.

The valve 11 continuing its course in the direction f!1 finally Vopens the orifices 391 (Fig. 3), so that the compressed air can stream into the channels 42 and 44 and from there in the direction f3 through the tube 46 onto the face |81 oi' the working piston 61.

It will be understood that in this construction the distributor 1 constitutes the equivalent of a driving device in so far as this distributor controls the action of the pressure iiuid on the approach piston 5 and on the working piston 6.

Finally, the said press is completed by a handle 43 of which an axial hole 44 extends the duct 42 for the admission of compressed air to the piston 61; the said handle 43 also permits adjustment of the initial position of the approach piston, 5 due to a screw threaded part 45 in which isvscrewed a screw threaded extension 46 of the said approach piston 5.

This press operates in the following manner:

(a) Approach stroke-Compressed air is admitted on to the face |61 of the approach piston 5, thereby producing a displacement of the said l piston 5 in the direction f6 (Figures 2 and 5).

The approach piston 5 drives the transmission liquid which then flows through the orifices or ports 25, 33 and displaces the movable head 3 in the direction f5.

During the said displacement of the approach piston 5, the pressure of the transmission liquid increases, thereby raising the piston 30. The valve 26 is thus freed so that at the end of the stroke of the approach piston 5, after the pressures on both sides of the orifices 25 have been stabilized the said valve 26 becomes reclosed under the action of its spring 21.

When the approach piston 5 is at the end of its stroke, the movable head 3 becomes displaced by the amount (a) (approach stroke; Fig. 5).

(b) Working stroke-Compressed air continues to be admitted on the piston 61, the said air no longer driving the approach piston 5, which has arrived at the end of its stroke but displacing the piston 61 in the direction f6 (Figures 5 and 6).

At the beginning of the stroke of the said piston 61, the working piston 62 closes the ports 33 and slides in its cylinder 20 thereby driving the transmission liquid into the cylinder 8 of the movable head 3 which thus becomes displaced during the first part of the Working stroke by a further amount t1y (Figure 6) corresponding to' the beginning of the riveting voperation (Figure 8).

`piston 62 closes the ports 33 in the cylinder 20 and then creates a depression in its rear and simultaneously in the annular space 32 and chamber I1. Consequently the valve 26 opens under the pressure of the liquid in chamber |11, whereby the depression which tends to develop at the right side of piston 62, is compensated.

'I'he communication between the chamber I1 and the chamber |11 is ensured during the return stroke by the action of spring 3| lifting valve 26 from itsseat.

'I'he working piston 62, 63 has a stroke greater 15 than the length of the working cylinder 20. `As soon as the working piston 62 leaves its cylinder 20 (Figure 6), the displacement of the movable head 3 is no longer ensured bythe said piston 61, but by the rod 63 of the said piston which then forms a working plunger piston. At this instant the pressures between the annular space 32 and the cylinder 8 of the movable head 3 become stabilized so that the pressure in this annular space 32 increases, thereby causing closure of the valve 26 (Figure 6) assisted by its spring 21.

The transmission liquid then becomes totally enclosed in the working chamber formed by the chamber i12 and the cylinder 8;" consequently the 15 movable head 3 becomes displaced by an amount t2 under the action of the pressuredue to the penetration of the rod 63 forming the plunger piston in the working chamber |11. The displacement t2 of the movable head corresponds to the 20 termination of the riveting operationv (Figures '1 and 8).

Since the section of the rod 63 is smaller than that of the piston 62 the force which acts on the movable head 3 during the portion of the stroke t1 is greater than the force which acts on the said movable head 3 during the portion of the stroke t1. v

It has been specified that the diameter D of the working piston 611s smaller than the diameter I D3 of the cylinder 8. During the iirst part of the working stroke the large section 62 of the working piston 6 becomes displaced in the working cylinder 20 forming a joint with it, while during the second part of the working stroke, the smaller section 63 of the working piston 6 moves freely in the working cylinder 20 and in the chamber I4 of the movable head 3, thereby producing the high pressure necessary towards the end of the working operation.

To sum up, the working piston which after the action of the approachpiston operates on the transmission liquid in order to create the working pressure, operates successively through several sections of different magnitudes, to each one l of which there correspondsa diiferent working pressure. Y According to the invention a process is therefore put into operation for the working of amet'al under the action of a driving force such as the pressure ofcompressed air and of`a liquid operating at constant volume, which process is characterised by the feature that a force of constant pressure is developed in order to ensurethe approach of a working tooland then forces are def veloped with. successive pressures of different values during the working operation, This permits the pressure force diagram and the useful working diagram of the metal to be rendered as identical as possible and consequently` permits the loss of energy in the execution of the working operation to be reduced to the minimum.

In order to return all parts of the device to their inoperative positions the lever 33 of the distributor 1 is released, whereupon the valve 11 connects the ducts 4| and 42 (Fig. 3) with the atmosphere through duct 38, andthe action of the compressed driving medium on the approach u contained in chamber I4 towards chamber' nz 4ing chamber |11'(Flg ure 11).

. A 1 'and |11', whereby the approach piston 5 is returned into its inoperative position in a direction opposite to f6. The'communication between the chambers' l12 and |11 is secured by the valve 26 which is kept open by the bottom of the regulating piston 30. .The return spring 3| 'of the piston 30 exerts a pressure in the direction `f1 superior to that of the return spring 21 of valve 26.

In particular Figure 8 shows that: the increase in the work obtained with respect to a press that comprises only two operating phases aand t, is equal to the area GDIH. v f In the above example, the said method has been applied in particular to the crushing of a rivet 2 joining two plates, the successive pressure forces having increasing, values during the working operation. Various modifications may be introduced into the riveting press above described by, way of example without thereby departing from the scope of the invention.

In particular in the press shown in Figures 9-11, the two different sections 61, 63 of the working piston I are connected to one another through a part 6 4-of very small diameter 'e. In this way inv the rst part t1 of the working stroke t, the liquid is conducted from the feed chamber |11 behind the section 61 of large diameter Ds of the working piston (Figure 10). Y

The liquid yfrom chamber |11 passes freely in the annular space left between the thin portion 6* of the piston rod Aand the package joint 2|, as long as the part 63 of the piston rod with the diameter ds does not engage said joint 2|.

In this way a constant filling of the liquid behind the said section 62 is ensured. y

Moreover, during thesecond part of the working stroke, the section 611 of small diameter of the working piston 6 engages exactly in the joint 2|` separating the feed chamber |11l from the work- Before the working stroke t, the ports 33, 34 discharge on both sides of the large section 61 of the working piston (Figure 9). Communication between thejfeedchamber |11 and the movable head 3, is thus ensured, the said head 3 then executing its approach stroke only underthe action of the approach piston 6.

Moreover, this arrangement permits the liquid .to return to the feed 'chamber l |11 after the working stroke. y

To sum up, a working stroke is obtained as previously, comprising two phases t1 t1; the phase t* during which .theworking head receives an increased force corresponds to the termination of the riveting-operation.

The press shown in Figures 12-14, is similar to those previously described with respect to the principal cylinder 4, the approach piston 6, the working piston l and the distribution members (notshown). .l

On the other hand this press differs vfrom the presses above described in the arrangement of the movable head 3 and the working chamber |11 as well as in the method of operation of the approac piston I on the movable head 3.

The working chamber |12 comprises two parts |14 I1s ofthe same diameter connected by a widerpart |11. y

A'by-pass 41l puts the said wider part |13 of the working chamber ,|11 into communication with the cylinder 8 at apart ofthe said cylinder situated at the rear of the maximum stroke of the movable head.

'I'his press operates in the following manner:

The approach stroke a' is obtained asl pre- 15 i vi'ously described, the approach piston 3 driving the transmission liquid towards the vmovable head 3.

As soon as this approach stroke a is completed, the working piston 62 penetrates into the ilrst part il4 of the Working chamber II2 (Figure 13) and increases the pressure of the transmission liquid in the said chamber, this pressure being transmitted equally to the two faces 31 32 of the 'movable head 3 due to the by-pass 41.

The movable head 3 then becomes displaced with a force which arises from the difference between the pressure forces on its face 31 oi diameter D1 and on its face 32 of annular section width D1-d1.

If p denotes the pressure per unit area, the resultant force f on the movable head 3 is equal When the working piston 62 passes the part |13 of the working chamber (Figure 14) the rear part of the cylinder 8 is put into communication with the part |14 of the working chamber II2 through the by-pass I1. Consequently the pressure on the face 32 of the movable head decreases suddenly and returns to the low value given by the approach piston 5.

The value oi this residual pressure of the face 32-on the movable head, can. be neglected so that the said movable head is displaced with a force corresponding to the action of the pressure over the whole of the surface of diameter D1', or:

1n-1 F- -4 Xp The movable head 3 thus constitutes a diilerential piston, the opposite faces of which are in communication with the working chamber I1.v

the larger Aface 31 communicating directly with the said chamber |12, while the smaller face 3fI .communicates with the said 4chamber |11,l bwa.

means of a by-pass 41 which discharges into a region |13 oi' the said working chamber separated from the movable head 3 and subjected to low pressure after a certain movement oi' the working piston 32. Consequently. during the rst part of the working operation, the pressure produced by the working piston 62 acts in a dmerential manner on the movable head 3, the displacement of the said movable head being then ensured only bythe reduced working section of the said head 3, while during the second part o! the working operation the pressure producedA by the working piston 62 operates on the whole section of the movable head 3. e

In this way a force ,f is ilrst produced corresponding to the ilrst working phase t1, and then an'increase force F is produced corresponding to the ccmpletion of the said working operation.

In other words during the working operation the movable .head 3 presents diilerent working sections D1 d1 upon which the pressure of the 4 liquid is exerted, this difference of working section permitting forces of different pressures to be cations, a transmission cylinder, a chamber containing a transmission liquid and in communication with said transmission cylinder, an approach piston slidably mounted in said transmission cylinder to exert a pressure on the liquid in said transmission chamber, a single working cylinder in communication with said transmission chamber, a working piston arranged for sliding displacement in said working cylinder and having a stroke greaterl than the length of the latter, said working piston having a plurality of working sections of diierent diameter to exert pressures of different values on the transmissionliquid, the smallest section of said Working piston dening an annular space between itself and the working cylinder, means for placing said annu-i lar space in communication with said transmission chamber, a driving device to actuate successively the approach piston and the .working piston, control means for said driving device to control the successive actuation of the approach piston and the working piston, a cylinder receiver connected with said working chamber, and a movable working head displaceably arranged in said cylinder receiver and subject to the action of the transmission liquid.

2. In a press for riveting and similar applications, a transmission cylinder, a chamber containing a transmission liquid and in communication with. said transmission cylinder, an approach piston slidably mounted in said transmission cylthe cylinder receiver rst to form a packed joint in the workingl cylinder so as to develop low pressures and`thereafter to become ineiective upon moving out of said working cylinder, a driving device to actuate successively the approach piston and the working piston, control means for said driving device to control the successive actuation of the approach piston and the working piston, a cylinder receiver connected to the working cylinder and in alignment therewith for receiving said'worklng piston, and a working head displaceably arranged in said cylinder receiver and subject to the action of the transmission liquid.-

3. In a press for riveting and similar applications,l a chamber containing a constant volume oi transmission liquid, a partition with a passage oriilce dividing said transmission chamber into two parts, an upstream part and a downstream part, the latter forming a single working chamber, a valve controlling said passage oriilce andopening towards said down stream part oi' the transmission chamber, a transmission cylinder connected to the upstream part of the transmission chamber, an approach piston slidably ses` ent diameters, the section of larger diameter ccntrolling the communication between the working cylinder and the downstream part of the transmission chamber, and the ,section of smaller dimeter producing an increased pressure in the -downstream part of the transmission chamber 4. In a press for riveting and similar applications, a chamber containing a constant volume of transmission liquid, a partition with a passage orice dividing said'transmission chamber into two parts, an upstream part and a downstream part, the latterforming a single working chamber, a valve controlling said passage orice and opening, towards said downstream part oi' the transmission chamber,.a transmission cylinder connected to the upstream part of the transmission chamber, an approach piston slidably mounted in said transmission cylinder to exert a pressure on the transmission liquid, a single working cylinder mountedin the downstream part of the transmission chamber and in communication therewith, a working piston slidably mounted in the working cylinder and having two sections of dierent diameters, the section of larger' diameter controlling the communication between the working cylinder and the downstream part of the transmission chamber, and the section vofl smaller diameter dening an annular space between itself and the working cylinder, means for -placing said annular space in communication 'with said transmission chamber, a driving device to actuate successively the approach piston and the working piston, control means for said driv- 'ing device to control the successive actuation of the approach piston and the working piston', a cylinder receiver connected with said working chamber and a working head displaceably larranged in said cylinder receiver and subject to the action of the transmission liquid.

5. In a press for riveting and similar applications a chamber containing a constant volume of transmission liquid, a partition with a passage orifice dividing said transmission chamber into two parts,an upstream part and a downstream part, the latter forming a single working chamber, a valve controlling said passage crince and opening towards said downstream part of the transmissionchamber, abutment means controlling the position of the valve and controlled by the liquid in the upstream part of the transmission chamber, a transmission cylinder connected to the upstream part ofthe transmission chamber, an

approach piston slidably mounted 'in said trans-y mission cylinder to exert a pressure on the transmission liquid, a single working cylinder mounted in the downstream part of said transmission chamber and in communication therewith, a working piston slidably mounted inthe working cylinder,- said working piston comprising two sec tions of dierent diameters, the section of larger .diameter controlling the communication between the working cylinder and the downstream part of the transmission chamber and the section of smaller diameter producing an increased pressure in the downstream part of the transmission chamber and closing said valve, when the larger section during displacement of the working piston v has become ineffective upon moving'out of the working cylinder, a driving device to actuate successively the approach piston and the Working piston, control means for said driving device to control the successive actuation` of the ,approach piston and the working piston, a cylinder receiver connected with the working chamber, and a working head displaceably arranged in said cylinder receiver and subject to the action of the transmission liquid. 6. In a. press tfor riveting and similar applications, a chamber containing a constant volume oi' transmission liquid, a partition with a passage orice dividing said transmission chamberinto ,two parts, an upstream part and'a downstream part, the latterforming a single working chamber, a valve controllingsaid passage orifice and opening towards said downstream part ofthe transmission chamber, a control cylinder connected to the upstream part of the transmission chamber, a control-piston slidably mounted in said control cylinder and arranged to abutv against said valve, a' spring urging said control piston against said valve'in order to open the latter, a transmission cylinder connected to the upstream part of the transmission chamber, an approach piston slidably mounted in said transmissioncylinder to exertl a pressure on the transmission liquid, a single working cylinder mounted in the downstream part of the transmission chamber and in communication therewith, a working piston slidably mounted in the working cylinder, said working piston comprising two sections of dierent diameters, the section of larger diameter controlling the communicationbetween the working cylinder and the downstream part of the transmission chamber and the section of smaller' diameter producing an increased pressure in the downstream part of the transmission chamber and Vclosing said valve when. the larger section during.y 

